I've been thinking a lot about what PS3 and Xbox 360 games will look like. The disappointing first generation of 360 titles hasn't answered the question, so I've been chatting to programmers about their next-generation projects. "The increase in processing power and demands for more realism will mean lighting becomes the natural focus," said one.

Lighting? I thought it was going to be photorealistic texture maps or billion-polygon 3D models. But no. We're going to see videogame artists using light in the same way as great chiaroscuro painters and cinematographers, employing subtle shades and cadences to bring life, three dimensionality and atmosphere to each scene - rather than bunging enormous coloured explosions around the screen.

A key technique will be high dynamic range (HDR) lighting, a processor-intensive means of simulating the vast range of luminescence perceptible to the eye. Usually, this range is hopelessly reduced on conventional and flat screens, but HRD lighting allows a greater contrast in extreme conditions, letting the player pick out scenic details in very bright and very dark environments.

This may sound trivial, but light has become important in games. Stealth adventures such as Thief and Splinter Cell require you to seek out shadow, to use shade as a form of camouflage. With next-gen lighting, this is about to become infinitely more complex. In the survival horror genre, you spend most of your time creeping about in the dark. Imagine how much more disturbing it would be if you could enter a room and gradually make out, from shadows in the corner, the outline of a lurking figure. Processing power, you see, is all about subtlety.

HDR lighting also allows for the over-saturation of brightness - to mimic scorching sunshine, for example. A few PS2 and Xbox titles toyed with this effect, notably Ico, but it will be huge on PS3 and Xbox 360. Two forthcoming PS3 horror titles - Resident Evil 5 and Possession - have abandoned the usual gloomy environments to take advantage of this effect: both are set in hot weather and look to capture the sickly nausea of relentless heat - the disorientation of walking outside and being momentarily blinded by daylight. Expect Summer Horror to be a major genre next year.

Advanced lighting will change the way designers think and, consequently, the way games work. Other effects, like subsurface scattering, which mimics the way light permeates semi-translucent objects such as human skin, and ambient occlusion, which adds ambient and reflected light to objects, creating a more harmonious mise-en-scene, will provide game worlds of varied texture and depth. This, hopefully, is what the next generation will be about. This is why light must be the focus.

· If you'd like to comment on any aspect of Technology Guardian, send your emails to tech@guardian.co.uk